The invention belongs to the technical field of terahertz wave imaging, and provides a terahertz wave imaging device. The device comprises a sample stage for supporting samples needing to be detected, a terahertz wave radiation source, a lens for focusing terahertz lights to a focal point, a first off axis paraboloidal mirror for transforming terahertz lights into parallel terahertz lights, a reflector for reflecting parallel terahertz lights, a second off axis paraboloidal mirror for focusing reflected parallel terahertz lights to a sample needing to be detected, a chopper for carrying out a chopping modulation process on terahertz lights, a detector for inducting energy changes of all detecting points of terahertz lights and then producing corresponding electrical signals of the detecting points, a signal processing unit for amplifying electrical signals of detecting points to carry out analogue-to-digital conversion processing to produce multiple resulting values, and a display terminus for carrying out imaging and display processes on samples needing to be detected through scanning and imaging software. The terahertz wave imaging device can realize a long-distance detection and is suitable especially for the situation that a suspicious object is carried out a safety inspection.